So I wanted to write an SCP but I feel as if it is similar to SCP-2006. My original idea was to make an SCP that can shape-shift into any living thing but then I saw the entry for 2006 and thought it might seem like I'm copying 2006.

My original idea was to make an SCP that can shape-shift into any living thing

Yeah, this is too bland. Take a look at the articles tagged with "metamorphic". It's a fairly well-covered topic, and if that's all your SCP article has, that's not going to be enough to get the audience's attention.

Why do you want to write a shapeshifter? What new aspects can you bring to that writing formula that haven't been seen before?